softwarecontainer.py: fix test_lib_exists
softwarecontainer.py: fix test_lib_exists

Test failed due to change of libsoftwarecontainer version.
Using symlink to library instead of library full name.

Signed-off-by: Tariq Ansari <dad672abc2e4079f76b3a3bd368bb45008914527@luxoft.com>

Pelagicore/meta-bistro,Pelagicore/meta-bistro,Pelagicore/meta-bistro,Pelagicore/meta-bistro,Pelagicore/meta-bistro,Pelagicore/meta-bistro